This invention relates to an apparatus for selectively releasing drop markers from an aircraft so as to identify or mark a particular point along a fight path. More specifically, this invention relates to a drop marker system for aerial operations such as spraying or seeding wherein a drop marker is ejected from the aircraft at the completion of a pass across the area being treated in order to indicate the boundary of the treated area and allow the pilot to execute an additional series of passes that result in substantially continuous and uniform coverage of an intended area.
Prior art drop marker systems for operations such as aerial seeding and spraying typically utilize drop markers that are formed by a relatively long flexible streamer that extends from a heavier, generally inflexible base member. In most such prior art arrangements, the base member is fabricated of a sheet material and each drop marker is arranged into a relatively compact storage package by positioning the streamer alongside the base member in a series of accordian-like folds. See, for example, U.S. Pat. No. 3,428,019, which issued to Tillay et al. on Feb. 18, l969. A typical prior art drop marker system is disclosed, for example, in U.S. Pat. No. 3,470,869, which issued to Tillay et al. on Oct. 7, 1969, wherein a single-file series of the folded drop markers is placed within a dispenser that is operable for ejecting a single drop marker in response to a pilot-initialed signal and is mounted on a wing or other portion of the aircraft.
When the pilot activates a system of the above-described type, a drop marker is ejected from the dispenser and passes into the relatively high velocity air that flows along the exterior of the aircraft. If the drop marker deploys properly, the heavier base member travels rearwardly in the airstream and falls downwardly to unfold the streamer and pull it into a fully extended condition prior to the time the drop marker reaches the ground. Thus, proper operation of the system provides a highly visible indicator that can be seen readily even when the area being treated is covered with crops or foilage of a fairly substantial height.
One drawback of such prior art drop marker systems is that the streamer does not always unfold to the fully extended position and the drop marker may land in a small pile that cannot be seen from the aircraft. This problem is addressed by several prior art drop markers systems, including the arrangement disclosed in Huwe, U.S. Pat. No. 3,973,513, wherein holes in the drop marker base member are intended to create air turbulance that causes the streamer to fully deploy as the base member plummets toward the ground. In another prior art proposal that is disclosed in Taylor, U.S. Pat. No. 4,261,283, the base member is configured to split into two separate pieces after release from the drop marker dispenser, with the two ends of the streamer being attached to separate pieces of the base member. In concept, the two pieces of the base member will attain spatial separation and fall to the ground with the streamer extended therebetween. Although providing a partial solution to the problem of streamer deployment, the prior art has not achieved the degree of reliability that is needed and desired in many situations in which drop markers are employed.
Another drawback that can be encountered with prior art drop marker system is that the drop markers do not always properly advance through the dispenser so that a drop marker moves into position for release as the preceding drop marker is ejected. Although air pressure and compression springs are often used to urge the stored drop markers toward the dispenser ejection mechanism, and although the drop marker base members are generally shaped to reduce frictional contact and jamming within the release mechanism, this particular problem has not been eliminated or alleviated to the desired degree.
It is therefore an object of the present invention to provide a drop marker system using drop markers with folded streamers wherein there is a high probability of the streamer unfolding as the drop marker is released from the dispenser mechanism and travels toward the ground.
It is another object of this invention to provide a drop marker and dispenser system that exhibits improved performance relative to the reliability with which drop markers advance through the dispenser and are ejected therefrom.
It is a further object of this invention to provide a drop marker system that substantially achieves the above stated objectives while being economical to fabricate and being relatively easy to operate and maintain.